Electrolytic grinding machine



1963 P. J. ROBISCHUNG ET AL 3,115,454

ELECTROLYTIC GRINDING MACHINE Filed Jan. 3, 1961 INVENTORS Philip J.Robischung BY Donald E. Sufron a Q, M... M wag ATTORNEYS United StatesPatent 3,115,454 ELECTROLYTIC GRINDING MACHINE Phiiip J. Robischung,Kalamazoo, and Donald E. Sutton,

Cornstock Township, Kalamazoo County, Mich, as-

signors to Hammond Machinery Builders, Inc., Kalamazoo, Mich., acorporation of Michigan Filed Jan. 3, 1961, Ser. No. 80,378 2 Claims.(Cl. 204-424) This invention relates to an electro-decomposition,metal-removal machine and it relates particularly to means for supplyingan electric potential of constant polarity to the spindle of such amachine wherein said spindle also carries the armature of aninduction-type, driving motor.

The present invention was developed in connection with electrolyticgrinding machines and, accordingly, both the specific problem involvedand the solution for same will be discussed in connection with suchmachines. However, it will be recognized that the principles of theinvention will be applicable to other types of apparatus, especiallymetal cutting apparatus, and, accordingly, the use of the specificexample mentioned will be recognized as illustrative only, not limiting.

In the design of electrolytic grinding machines it has been founddesirable to utilize the spindle upon which a grinding wheel is mountedas the support for the armature of the driving motor. This hasadvantages which are well known in the art. Particularly, theseadvantages include economy of space, elimination of driving mechanismconnecting the motor to such spindle and minimizing the number ofrunning parts which require care and maintenance This type ofconstruction is used for both single end and double end grindingmachines, that is, machines having one grinding wheel at one end of thespindle and machines having two grinding wheels mounted at opposite endsof the spindle.

When such a construction is used on an electro-decomposition type ofmetal-removal machine, it is necessary to apply a potential of constantpolarity to the spindle so that the potential is applied to themetal-removal tool, such as a grinding wheel which is electricallyconductive except for the abrasive grain, which wheel is used forelectrolytic grinding. This arrangement first raises the problem ofproviding ample protective insulation between the field windings of themotor and the spindle in order to protect the operator from the A.C.potential applied to the field windings, normally 220 or 440 volts, inthe event of a breakdown in the field winding insulation.

In addition, there is the problem of providing the proper point andmanner of application of the DC. potential to the spindle. Where only asingle end grinding machine is used, this presents no great difiicultyinasmuch as the DC potential can be applied to the spindle byconventional slip ring means located at the opposite end of the spindlefrom the grinding wheel. However, for double ended grinding machines,this technique is not available because the space otherwise occupied bythe slip ring must now be utilized for the second grinding wheel. Inorder to minimize deflection, the grinding wheel should be placed asclose as possible to the bearings and, therefore, it is not desirable toplace the slip ring between a spindle bearing and the grinding wheel. Toplace another bearing outwardly of the motor bearings in order to have abearing support closely adjacent to the wheel is likewise undesirablebecause it adds to the expense of the machine and increases the overalllength.

Accordingly, the objects of the invention include the following:

(1) To provide a spindle support and drive mechanism adaptable fordriving an electrical cutting tool, such as a "ice grinding wheel usedin electrolytic grinding wherein said spindle carries the armature ofthe driving motor and wherein means are provided for applying a DC.potential to the spindle at a point between the motor bearings andelectrically insulated from the field windings.

(2) To provide a spindle support and driving mechanism, as aforesaid,wherein the end bells supporting the motor bearings are suitablyinsulated from the central housing supporting the field windings toprovide protection of the machine operator in the event of breakdown ofthe field winding insulation. Such insulation also serves to isolate theA.C. and DC. potentials from each other and particularly prevents theD.C. potential used for the electrolytic operation from leaking toground through the central housing.

(3) To provide a spindle support and driving mechanism, as aforesaid, inwhich the spindle bearing adjacent the source of DC. potential isinsulated from the end bell by which it is supported to eliminate flowof current through the bearing and consequent etching thereof.

(4) To provide a spindle support and driving mechanism, as aforesaid,including means for applying a DC. potential to the spindle at a pointthereon between the field windings of the motor and one of the spindlebearmgs.

(5) To provide a spindle support and driving mechanism, as aforesaid,which is compact and space-saving and which can be manufactured atminimum cost.

(6) To provide a spindle support and driving mechanism, as aforesaid,which will be of maximum simplicity and which will require a minimum ofchanges from the motor construction previously used for nonelectrolyticapparatus.

(7) To provide a spindle support and driving mechanism, as aforesaid,which can be readily changed from an electrolytic application to aconventional or nonelectrolytic application or vice versa with a minimumnumber of changes in the parts of the mechanism.

(8) To provide a spindle support and driving mechanism, as aforesaid,which will be effective and capable of long operation with relativelylittle maintenance.

Other objects and purposes of the invention will be apparent to personsacquainted with devices of this general type upon reading the followingspecification and inspecting the accompanying drawings.

FIGURE 1 is an end, elevational view of the spindle and motor unitembodying the invention.

FIGURE 2 is a sectional view taken on the line IIH of FIGURE 1.

General Description The invention comprises placing a brush and slipring assembly within a suitable extension of one of the end bells of themotor housing between the bearing carried by said end bell and the fieldwindings. An insulating ring is placed between each end bell and anadjacent end of the cylinder defining the central part of the motorhousing within which the field windings of the motor are mounted. Thus,a breakdown in the insulation of said field windings will not apply thefield winding potential onto the end bells or the grinding wheelspindle. When the motor is to be used with a conventional grinder, it isnecessary only to change the end bell carrying the brush and slip ringassembly and replace same with a conventional end bell. In such case,the insulation between the end bells and the central casing may beremoved or retained as desired.

Detailed Description Referring now to the drawings, there is shown amotor housing comprising a pair of end bells 2 and 3 and a centralcylindrical casing 4 located between said end bells and secured thereto.Rings 5 and 10 of electrical insulating material insulate the end bells2 and 3 from the casing 4. A plurality of field windings 6 for the usualintroduction type or squirrel-cage motor are mounted on and within thecasing 4. In use, the casing 4 will ordinarily be grounded forprotection of the operator. The rings 5 and serve to insulate the A.C.potential on the field windings from the DC). potential applied on theend bells 2 and 3 as hereinafter described, and serve to insulate saidend bells from the ground connection provided by the casing 4.

The end bell 2 includes a section 7 which is substantially cylindricaland preferably of the same outside diameter as that of the cylindricalcasing 4. Said portion 7 is connected by a radially arranged wall 8 to afurther cylindrical section 9 within which are mounted suitablebearings, here the ball bearing units 11 and 12. Sealing means 13 of anyconvenient type, here shown as being of the interfitting flange andgroove type, are provided at the outboard end of the section 9 toprevent entry of grinding fluid and/ or grinding dust into the abovementioned bearings.

The end hell 3 comprises a generally cylindrical section 14 generallysimilar to the section 7 of the end bell 2 but being of somewhat greateraxial length. Further, the section .14 has three radially extendingtubular openings 16, 16a and 16b therein (FIGURE 1). Said end bell 3also has a radial wall 17 connecting the cylindrical section 14 with afurther cylindrical section 18 of reduced diameter. Bearing means 19,here a ball bearing assembly, is supported within section 18. Aninsulating sleeve 21 surrounds the bearing means 19 and insulates samefrom the end bell 3. This prevents flow of current (bypassing thehereinafter-menti-oned brush and slip ring assembly) through the bearingmeans which might otherwise cause etching of the bearing balls and/ orthe races and thereby destroy the bearing. This is a serious problem forthe bearing located adjacent the slip ring and brush assemblies,hereinafter described, but it is not a problem for the bearing units illand 12 in the end hell 2, in view of the insulation between end bell 2and easing 4. Therefore, it is not necessary to use an insulating sleevearound these latter bearings.

A further sealing assembly 24 of any convenient type, here shown asbeing of the interfitting flange and groove type, is provided outwardlyof the section 18 to prevent entry of grinding fluid and/or grindingdust into the bearing 19.

A rotor 25 is disposed within the field windings 6 in the mannercustomary for induction motors so that energization of said fieldwindings will eflect rotation of said rotor. The rotor 25 has a spindle26 secured thereto and extending therethrough and beyond both axial endsthereof. One end portion of the spindle 26 extends through and issupported by the bearings 11 and 12 while the other end portion extendsthrough and is supported by the bearing 19. Grinding wheels 27 and 28are mounted on the respective axial ends of the spindle 26. The spindle26 and rotor 25 serve as the armature of the motor which includes thefield windings 6. Thus, energization of the field windings will rotatethe spindle 26 and thereby rotate the grinding wheels 27 and 28.

An electrically conductive slip ring 31 is secured to the spindle 26-and is located within the section 14 between the bearing 19 and theadjacent end of field winding 6. Brush units 32, 32a and 32b aredisposed in the radial openings 16, 16a and 16b, respectively. Since thebrush units are substantially identical, only unit 32, which is disposedin opening 16, will be described in detail herein. It will be understoodthat this description applies also to the other brush units. Brush unit32 includes a brush 33 slidable within opening 16 and having an arcuateinner edge slidably engageable with the periphery of slip ring 31. Aconductor 34 is secured to the brush 33 and extends outwardly through acentral opening in the plug 36. A spring 37 surrounds the conductor 34and bears at its inner end against the outer edge of brush 33 tocontinuously urge same against the slip ring 31. The outer end of spring37 bears against a shoulder within the plug 36.

The conductors 34 and 34a of the brush units 32 and 32a are connected toa terminal post 41. The negative side of a source of DC. potential isconnectible to the post 41 while the positive side thereof isconnectible to the workpieces as is conventional in electrolyticgrinding procedures. Thus, the brush units 32 and 320 are intended tosupply electrical potential for the spindle 26 and thereby to thegrinding wheels 27 and 28.

The conductor 34b of the brush unit 32b is connected to a terminal post42. A conductor (not shown) may connect the post 42 to the electriccurrent control unit (not shown) which controls the amperage flowingthrough the spindle so that the proper amperage will flow through thespindle, all in accordance with conventional electrolytic grindingpractice.

In use, A.C. potential applied to the field windings 6 will eifectrotation of the spindle 26 and thereby rotation of the grinding wheels27 and 28. Electrical energy supplied to post 41 will travel throughconductors 34 and 34a, thence through brushes 33 and 33a, the slip ring31 and the spindle 26 to the grinding wheels 27 and 28. The insulatingrings 5 and '10 isolate the end bells 2 and 3 from the casing 4 so thatthe A.C. potential applied to windings 6 will be isolated trom the D0which is applied to the end bells and further, prevents the A.C.potential applied to the field windings, which is usually 220 or 440 v.A.C., from being applied to the end bells if the insulation of the fieldwindings should fail. While the end bells will carry DC. potentialapplied through the brushes 33 and 33a, this is of a low voltage andcannot harm the operator if he should touch said end bells. Theinsulating sleeve 21 will prevent the DC. potential on end bell 3 frompassing through the bearing 19.

If it should become desirable to convert the motor to use as anon-electrolytic grinder the same can easily be done by replacing theend bell 3 with another end bell corresponding to end hell 2 or itsequivalent.

While a particular, preferred embodiment of the invention has beendescribed in detail, the invention contemplates changes or modificationsthereof which lie within the scope of the appended claims.

What is claimed is:

1. Apparatus for removing metal by an electrolytic process, thecombination comprising:

an electric motor including an intermediate housing section having astator mounted therein;

a rotor mounted within said stator;

a solid spindle connected to said rotor and extending beyond the endsthereof and beyond the ends of said intermediate housing section;

a first housing end section having a bearing mounted therein, firstinsulation means between said first housing end section and saidintermediate housing section, said first end section being fixed to butelectrically insulated from said intermediate section, said spindlebeing rotatably supported adjacent one end thereof by said bearing andextending through and beyond said first end section;

a second housing end section having a second bearing mounted therein,second insulation means between said second housing end section and saidintermediate housing section, third insulation means between said secondhousing end section and said second bearing, said second end sectionbeing fixed to but electrically insulated from said intermediatesection, said spindle being rotatably supported adjacent its other endby said second bearing and extending through and beyond said second endsection;

an electrically conductive slip ring within said second end section andsecured to said spindle between said second bearing and the adjacent endof said stator,

said slip ring being electrically connected to said spindle but beingfree of electrical connection to the windings of said motor;

a brush mounted in said second end section and means urging same intosliding contact with said slip ring;

a source of DC. potential and means connecting one terminal of same tosaid brush, the other terminal thereof being adapted for connection tothe work pieces to be ground, said second bearing being insulated fromflow of electrical energy therethrough by said third insulation means;and

means for securing electrolytic grinding wheels to the respective endsof said spindle with at least one grinding wheel on said spindle.

2. An apparatus for removing metal by an electrolytic grinding process,the combination comprising:

an electric motor casing and a pair of end bells secured to the oppositeends of said casing;

electrically nonconductive means disposed at the opposite ends of saidcasing and electrically insulating said casing from said end bells;

a stator and a rotor mounted within said casing, said rotor having anelectrically conductive spindle connected thereto, said spindleextending through said end bells;

bearings within said end bells adjacent to the outer ends thereof androtatably supporting said splindle adjacent the ends thereof wherebydeflection and vibration of said spindle are minimized;

one of said end bells having a hollow, axially elongated sectionadjacent to one end of said casing and located between said casing andthe bearing in said one end bell;

an electrically conductive slip ring mounted on said spindle and locatedwithin said hollow section of said one end bell and axially inwardly ofsaid bearing therein;

said hollow section having an openin therethrough and a brush mountedWithin said opening and slidably engaging said slip ring whereby saidbrush means can supply electrical potential to said slip ring andthereby to said spindle;

a sleeve of insulating material surrounding said bearing in said one endbell and electrically insulating said bearing from said one end bellwhereby flow of electrical energy through said bearing is prevented; and

means for securing an electrolytic grinding wheel on each end of saidspindle respectively and closely adjacent said bearings, whereby radialdeflection of said grinding wheel is minimized, at least one grindingwheel being mounted on said spindle.

References tli ed in the file of this patent UNITED STATES PATENTS2,514,693 Chapman July 11, 1950 2,526,423 Rudorff Oct. 17, 19502,798,846 Comstock July 9, 1957 2,946,731 Falls July 29, 1960

1. APPARATUS FOR REMOVING METAL BY AN ELECTROLYTIC PROCESS, THECOMBINATION COMPRISING: AN ELECTRIC MOTOR INCLUDING AN INTERMEDIATEHOUSING SECTION HAVING A STATOR MOUNTED THEREIN; A ROTOR MOUNTED WITHINSAID STATOR; A SOLID SPINDLE CONNECTED TO SAID ROTOR AND EXTENDINGBEYOND THE ENDS THEREOF AND BEYOND THE ENDS OF SAID INTERMEDIATE HOUSINGSECTION; A FIRST HOUSING END SECTION HAVING A BEARING MOUNTED THEREIN,FIRST INSULATION MEANS BETWEEN SAID FIRST HOUSING END SECTION AND SAIDINTERMEDIATE HOUSING SECTION, SAID FIRST END SECTION BEING FIXED TO BUTELECTRICALLY INSULATED FROM SAID INTERMEDIATE SECTION, SAID SPINDLEBEING ROTATABLY SUPPORTED ADJACENT ONE END THEREOF BY SAID BEARING ANDEXTENDING THROUGH AND BEYOND SAID FIRST END SECTION; A SECOND HOUSINGEND SECTION HAVING A SECOND BEARING MOUNTED THEREIN, SECOND ISULATINMEANS BETWEEN SAID SECOND HOUSING END SECTION AND SAID INTERMEDIATEHOUSING SECTION, THIRD INSULATION MEANS BETWEEN SAID SECOND HOUSING ENDSECTION AND SAID SECOND BEARING, SAID SECOND END SECTION BEING FIXED TOBUT ELECTRICALLY INSULATED FROM SAID INTERMEDIATE SECTION, SAID SPINDLEBEING ROTATABLY SUPPORTED ADJACENT ITS OTHER END BY SAID SECOND BEARINGAND EXTENDING THROUGH AND BEYOND SAID SECOND END SECTION; ANELECTRICALLY CONDUCTIVE SLIP RING WITHIN SAID SECOND END SECTION ANDSECURED TO SAID SPINDLE BETWEEN SAID SECOND BEARING AND THE ADJACENT ENDOF SAID STATOR, SAID SLIP RING BEING ELECTRICALLY CONNECTED TO SAIDSPINDLE BUT BEING FREE OF ELECTRICAL CONNECTION TO THE WINDINGS OF SAIDMOTOR; A BRUSH MOUNTED IN SAID SECOND END SECTION AND MEANS URGING SAMEINTO SLIDING CONTACT WITH SAID SLIP RING; A SOURCE OF D.C. POTENTIAL ANDMEANS CONNECTING ONE TERMINAL OF SAME TO SAID BRUSH, THE OTHER TERMINALTHEREOF BEING ADAPTED FOR CONNECTION TO THE WORKPIECES TO BE GROUND,SAID SECOND BEARING BEING INSULATED FROM FLOW OF ELECTRICAL ENERGYTHERETHROUGH BY SAID THIRD INSULATION MEANS; AND MEANS FOR SECURINGELECTROLYTIC GRINDING WHEELS TO THE RESPECTIVE ENDS OF SAID SPINDLE WITHAT LEAST ONE GRINDING WHEEL ON SAID SPINDLE.